The invention relates to a current distribution device, particularly for motor vehicles.
Current distribution devices are used to distribute or branch electrical currents within a power supply network. To ensure that the current distribution is protected, it is advantageous to provide the current distribution device with fuses.
For this purpose, use has so far been made of fuse modules which are available in various standard fuse values and are screwed on to a current distribution component. This solution does, however, suffer from the drawback that a large number of individual parts such as screws, nuts, washers etc. is necessary and that assembly is very complex.
A cable fuse is known from WO 89/03117. This known fuse for cables comprises, in addition to an insulating housing, an integral metal element which connects together, via a fuse area, metal-coated plug-in connections for the purpose of insertion into corresponding cable ends. The subject matter known therefrom relates to a fuse; current distribution is not possible by means thereof and is not envisaged either.
The invention is based upon the technical problem of providing a simple-to-manufacture current distribution device, particularly for motor vehicles, and providing a method of producing such a current distribution device.
In accordance with the invention, this technical problem is solved by a current distribution device comprising the features of claim 1 or a current distribution device comprising the features of claim 6. The technical problem upon which the invention is based is also solved by a production method comprising the features of claim 13 or 14.
A current distribution device according to a first fundamental embodiment of the inventive concept comprises a first area made of electrically conductive material and having at least one electrical connection. Depending on where the current distribution device is placed within a power supply network, the following can e.g. be connected to the connection: current leads, a line to the positive pole of a battery, or a ground lead. If the current distribution device is arranged, for example, on a battery, the battery pole can also be directly connected to the connection. Such a current distribution device also comprises at least two separate areas likewise made of electrically conductive material.
The second areas are each connected to the first area via bridge-like fuse areas made of electrically conductive material. Each bridge-like fuse area is inseparably connected to the first area and to the associated second area. Each bridge-like fuse area also comprises a cross section of material calibrated along a longitudinal section by means of the material thickness and/or width. As regards each fuse area, the particular fuse value desired is defined by different calibrations of the cross sections of material exhibited by the bridge-like fuse areas. The fuse areas can be calibrated both by variation of the bridge length and by variation of the material thickness and/or width or by a combination thereof.
The second areas each comprise at least one electrical connection. Branching current leads can for example be connected thereto. Such branching current leads can be connected for example by means of crimp connectors, by welding, soldering or in any other suitable way.
In accordance with the invention, the inseparable connections of the bridge-like fuse areas to the first area and the respectively associated second area make any additional individual parts such as screws etc. superfluous and as a result the production of the current distribution device is correspondingly simplified. The fuse areas can be advantageously integrated into the current distribution device as a result of the fact that according to the invention, bridge-like fuse areas are provided instead of conventional fuse modules. This means that compact and weight-saving current distribution devices can be obtained.
The first area and the second areas are preferably made from a plate-shaped or band-shaped semifinished article. These areas can, however, also be made from other semifinished goods or produced by other suitable manufacturing techniques.
In an expedient design, the bridge-like fuse areas have the same thickness of material as those sections of the first area and of the associated second area which adjoin the bridge-like fuse area or they have a smaller thickness of material at least along a longitudinal section. In this way, the bridge-like fuse areas can be made from a semifinished article similar to the first and second areas or even from the same semifinished article. The fuse areas can, for example, be calibrated by punching out a specific longitudinal section with a specific width of material and optionally by additionally reducing the material thickness.
It is beneficial for the bridge-like fuse areas to be provided with a curved course at least along the longitudinal sections which exhibit the calibrated cross section of material, thus obtaining in a structurally compact manner that bridge length which is necessary for the desired fuse characteristics. Such a curved course may for example be S-shaped. In an alternative embodiment, a kinked course formed from straight partial sections is also suitable. A straight course of the bridge-like fuse area can also, however, be provided.
In an advantageous embodiment, the first area, the second areas and the bridge-like fuse areas of the current distribution device are integrally designed. This yields an integral current distribution device which is reduced to a single component, thereby dispensing with any complicated assembly work that has so far been necessary when screwing on fuse components. In this version, the current distribution device can be particularly realized as a punched and bent part based on a plate-shaped semifinished product, thereby achieving comparatively convenient production. The semifinished product used may e.g. be a semifinished copper product which can also be surface-treated, a semifinished product made from a suitable alloy or a semifinished product built up as a sandwich composed of different layers of material. An integral construction for the current distribution device can also be achieved by using other semifinished products or by means of other production techniques.
In another favorable embodiment, the bridge-like fuse areas are prefabricated as separate components and then inseparably connected to the first and the respectively associated second area of the current distribution device. In this way, the bridge-like fuse areas can be made e.g. from materials or alloys other than those used in the first area and the second areas of the current distribution device. The bridge-like fuse areas can also be produced and calibrated separately from the first area and the second areas.
In an advantageous embodiment, the bridge-like fuse areas are connected to the materials of the first and of the respectively associated second area by means of plastic deformation, e.g. by squeezing or calking. In other advantageous embodiments, the bridge-like fuse areas are connected to the materials of the first and of the respectively associated second area by means of a welding, soldering or riveting connection. The bridge-like fuse areas are therefore connected to the first and to the second area of the current distribution device in an inseparable fashion, i.e. they cannot be nondestructively separated. A considerable reduction in the number of parts required by the current distribution device is also obtained in these embodiments, because screws, washers etc. are dispensed with. The production of the inseparable connections between the fuse areas and the first and the second areas of the current distribution device can also be automated to good effect.
In an expedient embodiment, the bridge-like fuse area is made from a plate-shaped or band-shaped semifinished product, such as a semifinished copper product which is optionally surface-treated, a semifinished product composed of an alloy or a semifinished product built up as a sandwich.
As is evident from the above comments, the general designation of xe2x80x9cinseparably connectedxe2x80x9d, as used in the claims, therefore also covers a one-piece embodiment of the various functional areas of the current distribution device. Of course, it is also possible to provide not only one-piece integral connections of individual areas, but also subsequently produced connections of individual areas (by means of pressing, riveting etc.).
Depending on the installation factors for the current distribution device, this device may be designed to be flat, stepped or to exhibit any other suitable geometry. In the case of a stepped design, the connections may be located at different levels of height. In the case of a flat design, the current distribution device can be essentially designed on the plane of the semifinished product.
In another embodiment, the second areas have a lower thickness of material at their connections in order that comparatively small terminal contact members can also contacted by current leads, e.g. when crimp connectors are used.
A contact base on the first area and a contact base on the associated second area are preferably assigned to each bridge-like fuse area, the two contact bases that belong to a fuse area each being disposed adjacent to the fuse area and facing one another. Should the bridge-like fuse areas blow out, e.g. due to a short circuit or an overload, conventional fuse modules as repair fuses can then be attached to the contact bases which face one another in pairs in order to re-bridge the fused sites after eliminating the cause of fault. Depending on the design, such repair fuses can be screwed on, clamped, resiliently contacted or attached in any other way. The contact bases at the sides of the current distribution device correspondingly comprise bores for screwing on repair fuses, plug-in carriers for inserting repair fuses or similar fastening means.
In an expedient embodiment, the current distribution device is accommodated within a housing made of insulating material. The housing preferably comprises viewing windows in the region of the bridge-like fuse areas so as to allow the fuse areas to be visually checked.
According to a second fundamental embodiment of the inventive idea, a current distribution device according to the invention comprises a first area composed of electrically conductive material and at least one electrical connection. As in the first embodiment of the invention, different current leads, such as a line to the positive pole of a vehicle battery, can be connected to the connection, depending on where the current distribution device is placed within a power supply network. In this case, the current distribution device can also be placed directly on the battery housing so that the battery""s positive pole is directly contacted with the electrical connection of the first area.
The current distribution device according to the invention also comprises at least two second areas made of electrically conductive material and which each have at least one electrical connection. Bridge-like fuse areas which are likewise made of electrically conductive materials connect each second area with the first area. The bridge-like fuse areas are inseparably connected to the first area by means of deep-draw sleeves.
Deep-draw sleeves which serve to fasten the fuse areas to the first area of the current distribution device are therefore formed. The deep-draw sleeves can be arranged on that component which forms the first area. Or a deep-draw sleeve can be provided on each component that forms the bridge-like fuse area. In these two embodiments, the deep-draw sleeves are integrally formed on the selected component by a deep-drawing process or an equivalent plastic deformation process, i.e. either at the side of the first area or at the side of the fuse area. The connection between that component which forms the first area and that component which forms the fuse area is then made in each case by plugging the one component (provided with a corresponding through-aperture) on top of the other component with deep-draw sleeve(s) and by subsequent plastic deformation of the deep-draw sleeve""s free edge that has been inserted through. A close, inseparable and securely adjacent connection between the first area and the associated fuse area is created by this plastic deformation of the deep-draw sleeve""s free edge; such a connection also guarantees reliable current transmission.
It is also conceivable to form deep-draw sleeves at the sides of both components, e.g. as a result of the fact that a fastening section of the component including a fuse area is placed onto the other component which forms the first area, and the two components are pressed together to form deep-draw sleeves which plastically flow into one another.
The deep-draw sleeves are preferably integrally formed onto the first area and corresponding fastening sections of the bridge-like fuse areas are provided with suitable through-apertures which can be fitted onto the deep-draw sleeves. The free edges of the deep-draw sleeves are plastically pressed onto the attached fastening sections of the fuse areas to form an undercut. In this design, the components with the bridge-like fuse areas can be produced more easily, since all the deep-draw sleeves are then formed on the first area of the current distribution device.
In another preferred embodiment, the first area of the current distribution device comprises a carrier area and a holding-up area. The deep-draw sleeves are integrally formed onto the carrier area. The bridge-like fuse areas are provided with fastening sections. Both these fastening sections and the holding-up area each comprise suitable through-apertures that can be fitted onto the deep-draw sleeves. The free edges of the deep-draw sleeves are plastically pressed onto the fastening sections of the fuse areas and onto the holding-up device fitted thereon to form an undercut. In this design, the connection is therefore also reinforced by the holding-up area. The fastening sections of the bridge-like fuse areas are therefore clamped between the carrier area and the holding-up area of the first area. Pressing the deep-draw sleeves formed on the carrier area and projecting through the fastening sections and the holding-up area causes the holding-up area, fastening sections and carrier area to be pressed and fixed.
In the embodiment described above, the holding-up area is preferably connected integrally with the carrier area and folded by plastic deformation onto the deep-draw sleeves of the carrier area and onto the fuse-area fastening sections fitted thereon. The first area can therefore be integrally produced as a punched and bent part, the carrier and holding-up areas being connected for example by means of connecting webs at which the holding-up area is then folded relative to the carrier area. In an alternative embodiment, the carrier area and holding-up area can also be designed as two separate components which are then fitted on top of one another.
In a beneficial embodiment, the second areas are integrally formed with the associated bridge-like fuse areas. The second areas can, for example, be designed exactly like the fastening sections with which the fuse areas are attached to the first area. In this way, those components which each form the fuse area can e.g. be symmetrical in design, e.g. as strip-shaped components having two fastening sections between which the bridge-like reference rupture point of the fuse is located. The current distribution lines, which are each electrically fused by the fuse bridges, can then e.g. be directly contacted at those free fastening sections which face away from the first area.
In an alternative embodiment, the second areas, which serve the terminal contacting of current distribution lines, are inseparably connected to the bridge-like fuse areas. The second areas can be connected to the fuse areas in the same way as or in a manner similar to the connection of the fuse areas to the first area.
In an embodiment, a plurality of bridge-like fuse areas are integrally formed such that the fastening sections of the fuse areas are connected together in the area adjoining the first area. In this way, a plurality of fuse areas can be combined to form a component which is then connected to the first area.
In an advantageous embodiment, one or more terminal contact elements can in addition to the bridge-like fuse areas be inseparably connected, by means of plastically deformed deep-draw sleeves, to the first area. In this way, there may also be non-fused connection options parallel to the current distribution device""s connection options fused via the fuse areas. Of course, additional connection options can also be integrally provided on the first area of the current distribution device.
An intimate electrically conducting connection of a first area and fuse areas is obtained by the inventive design of sleeve-like projections which are deep drawn or integrally formed by a similar process, and assembly of the current distribution device is considerably simplified. The screw connections between the first area and the fuse areas are dropped, which means that the associated connecting parts such as screws, nuts, washers etc. are no longer necessary either since the sleeve-like projections are integrally xe2x80x9cdrawn out ofxe2x80x9d the material of the associated component. The current distribution device according to the invention can advantageously be produced in an automated production sequence.
In the current distribution device according to the invention, each pressed deep-draw sleeve preferably simultaneously forms a through-aperture. If a bridge-like fuse area is blown, i.e. fuses, during operation, this through-aperture of the associated deep-draw sleeve connection can be directly used to screw on a repair fuse. It is also conceivable, however, for the deep-draw sleeves to keep a closed base.
The fuse areas can be designed in various known ways and are calibrated for the particular current fuse value desired. The type of connection for the outgoing current leads to the second areas can also be designed in various known ways. The current distribution device according to the invention is very variable as regards different equipment versions, as required e.g. in motor cars. A wide variety of bridge-like fuse areas calibrated to different trigger characteristics can be inserted into a basic component that has a number of connecting sites in the form of deep-draw sleeves; these fuse areas are then securely connected by subsequently pressing the deep-draw sleeves.
The current distribution device can also be designed on different spatial planes so as to enable connection options at different spatial height levels. There is also provision for receiving the current distribution device within an insulating housing.
It goes without saying that the deep-draw sleeves explained above can also be used in a current distributor according to the first basic embodiment of the inventive idea in order to connect the fuse areas with the first and/or second areas.
As already explained, different materials including alloys or composite materials, such as copper, zinc or the like, are possible as regards the production of the current distribution device corresponding to the above two embodiments of the inventive concept. The fuse areas and the first and second areas can be made from identical or different materials. In a one-part design version of the current distribution device, the device is preferably made from aluminum or an aluminum alloy, e.g. aluminum with the alloy numbers 1030, 1035, 1040, 1045, 1050 or 1050A. Even in current distribution devices composed of several parts, it is possible to use aluminum materials, for example just for individual fuse areas.
In principle, two methods are advantageous in order to produce a current distribution device whose first and second areas and fuse areas have a one-part design.
The first production process according to claim 13 provides that the raw material band which is for example drawn off from a coil is milled in the region of the fuse areas to be shaped. After milling, the first and second areas as well as the fuse areas are punched out. During the process of punching out, variation of the width simultaneously calibrates the fuse areas, the thickness of which has already been determined.
A very similar production process is obtained in that the desired shaping of the first and second areas and the fuse areas is effected by punching them out. The fuse areas are then pressed into the thickness necessary for calibration. If need be, the fuse areas are then re-punched in order to perform final calibration of the fuse areas by varying the width.
Compared with the former method, this latter method enjoys the advantage that very different fuse values can also be calibrated in the fuse areas. The first method, however, has the advantage that it is possible to check easily the fuse-area thickness predetermined by milling.
Both production processes are beneficial to the extent that it is possible to produce the current distribution device using a band of raw material wound up as a coil, e.g. on a continuous machine with adjacent machining stations.
The choice of material for the one-part current distributor is expediently made with regard to the field of application and in accordance with the production process. A relatively hard aluminum, e.g. exhibiting a hardness in the range of 100-120 HV, is advantageous in the production process in which calibration is effected via a milling operation. If calibration is brought about by means of pressing, a softer aluminum, e.g. exhibiting a hardness in the range of 20-40 HV, is preferred.
Aluminum has proved to be very advantageous, since it was possible to use this material in tests to achieve very favorable courses of the fuse characteristics. Aluminum avoids thermal problems which may arise in materials with a high melting pointxe2x80x94as is the case with copper. Aluminum also enjoys the advantage that the current distribution device has a low overall weight, even if even somewhat thinner structural shapes appear possible using other materials like copper. Aluminum also performs very well compared with zinc, a material with an even lower melting point than aluminum, since it is possible to use aluminum to obtain a much thinner structural shape with a much lower weight.
In summary, it can be stated that one-part aluminum current distribution devices according to the invention are beneficial to produce, due to the fact that the material can be worked well and as a result of the fact that the devices can be produced in a continuous process. A weight-saving and compact structural shape is achieved with very good fuse characteristics, whereby different fuse values can be obtained in a current distributor. The terminal contacts can also be arbitrarily designed, e.g. as holes, lugs etc.
Due to aluminum""s oxidation properties, it is expedient to provide an aluminum current distribution device with an oxidation-inhibiting coating. Such a coating can assume various forms that are known per se, e.g. in the form of a zinc/copper/tin coating applied in successively connected, electroplating dip baths.
In the aforementioned production processes, it may be an advantage, when there is a plurality of second areas, for these second areas to remain connected together until the end by means of webs which are removed only after all the machining steps have been performed. This makes it possible to machine the current distribution device blanks in a more effective and stable manner.